I have a 1970 Bronco with the 302 engine. I have not started this engine in the last 5 years due to being tied up with other things. I find now that the engine is seized and will not turn over. Does this mean that the engine is shot or is there another way to free it up ? Will towing it while in gear free the engine or is there a better way ? I pulled all the plugs and disconnected the coil wire so it won't start, I just want it to turn over..........Thanks for any help ...Carl

I would at least spray some sort of penetrating oil into the cylinders to try to cut through the rust that is presumably got the rings stuck to the cylinder walls at this point.
If that's all the issue is, and it's fairly light rust still, it might free up enough to be loosened by hand and not mess up the rings after it starts (like sandpaper).

A lot of people have successfully done something like this, but not everybody is so lucky. Depends on what all happened, and if there was actually some serious water intrusion in one or more cylinders.

Good luck. Can't hurt at least! Spray a bunch in there and let it do it's thing for a day or two.
Or better yet maybe, pour some Evap-o-Rust in there and let it do it's magic. Or one of the similar products out there nowadays.

Thanks Paul....This engine ran very good when I last shut it down to work on the body and fix a leaking gas tank, it didn't use any oil and ran very smooth.. I have had this Bronco for almost 40 years now and really would ;like to get it back to where it was, I really like this Bronco.
I will try to put some penetrating in the cyl and see if it can break it loose. If it doesn't do you think towing it with it in gear would work without doing any damage ?
Thanks Again Paul

While I don't think it will damage anything other than dragging tires, it still "could" do something bad. Just not sure what. Depends on the condition of things in-between the business ends such as u-joints and the like.
Depends too on just how badly the engine is seized.

And you know it's seized, and not just stuck in gear, right? Just checking...
Good luck.

Thanks Paul.....Your first suggestion worked.....I sprayed the penetrating oil into each cyl several times without any luck but after several days it broke free and now seems to be turning over as it should. I still haven't tried to start it as I want to let it set with the oil in there and just rotate the engine several more times before I try to start and run it. I want to drain the oil and pull the valve covers off and pour some oil over the valves............Thanks for all your help Paul...I owe you one.....Carl

Great news!
Yeah, keep on spinning. Good to change all that other stuff now while you're messing about.
And in case you were not aware, you should be using a high-zinc oil in your old engine with a flat-tappet cam. Most oils these days are low on zinc because it's a known air pollutant and is not needed as much with all the new engines being rollerized so to speak.
But ours still need them, and they are available in most cases. In a pinch, a diesel rated oil is going to almost always be higher in zinc than a gas oil, but there are plenty of gas rated oils with it just for that purpose.
The weight ratings are the same, just the amount of zddp additives.

Would you have any name brands of this oil or any place where you might be able to get this oil ? I will be putting in new plugs, fuel pump, voltage reg, and starter relay among other things as I go. I really look forward to getting it running but want to take my time and do all I can to get it right. I will be painting it Candy Apple and White....a little loud for an old guy like me but I thing it will look good....Thanks Again.....Carl

Most brands of oils will have at least one version or another. Usually marketed as "high mileage" or "older car" or even "high zinc" oils. When in doubt, simply check the label and it will almost definitely specify "compatible with older flat tappet engines" or something to that effect.
And as I mentioned, when in doubt you can use an oil that's compatible with diesel engines. The "D" oils will have a high-zinc content too usually.

I was worried about availability since it was an emissions thing (especially around here) but need not have bothered. My local go-to store has what looks like 20 different versions in stock. All the common weights and brands in both synthetic and dino oils.

Another thing that does not take well to sitting for a long period is the fuel pump. Since you're replacing things like the starter already, I would do the pump if you haven't already.
In fact, I would not replace a starter unless it was acting up. If you think it got a little jacked trying to start the frozen engine, that's reason enough. But if it's sounding and acting good, it's likely still good for some time to come.

I really appreciate all this info... Paul....I am getting up there in age (will be 77 next month) so all this really helps. I do have one more question and then I won't bother you anymore. I would like to know if you still use the lead additive in the gas and if so where can you get it. It has been so long since I drove the Bronco but I know that I used to use it with each time I filled the tank. ...Carl

I don't use it because I had the heads redone with hardened exhaust seats a long time ago.
But until that point, and with other cars after, I used the Sta-Lube brand (I think?) that was in a special dispensing bottle that made it easy to meter out just enough for a tankful. It was a MUCH less expensive alternative to adding a full can of something to every tank.
I have not looked on the shelves of local parts stores lately though, so not sure it's still available.

Ford did use induction hardened seats (I believe even in '70?) so they are not as prone to recession as other engines might be, but it's still a good thing to upgrade to better seats when doing a valve job.
And a valve job is one of the things that nets some pretty good results in how an engine runs anyway, so a high-mileage motor is not a bad candidate for that.

I'm sure gone are the days of $200 valve jobs, but not sure what they cost these days.

Paul is too modest . He has an amazing Pool of knowledge when it comes to early Broncos and the ability to relay that knowledge .
Some of us read a question that's posted and debate about the best way to answer { i usually make mine too brief } and we're better at filling in the blanks or reaffirming a previous response.

When you come to a fork in the road - take it
Homer - " Facts are meaningless . You could use facts to prove anything that's even remotely true."

Paul has been a lot of help on this and I am thankful for any help I can get...I used to be pretty good at the mechanic stuff but I guess the age thing is catching up on me on some of this stuff. I for one am thankful for a site like this to get help from...Have a great Memorial Day everybody be safe and give thanks to all our Vets...Carl

Does it turn over by hand? Possibly the starter is just stuck or broken? Every climate is different but my recent purchase of a 74' that sat for 12 years, I put a battery in it and some fresh fuel and she popped right off (carb is plugged pretty bad but it will idle decent) I probably got pretty lucky though. Like said above make sure its not stuck in gear. Is yours a Standard or Auto Trans?

I finally got it to turn over. It started by just moving a little at a time and stop and then it would move more and more until it seems like it is turning over pretty free. I took off the valve covers and poured oil over the valves and just let it drain out the oil pan and poured it back in until it would turn over........I still haven't tried to start it as the fuel tanks have fuel in them that is very old. I want to somehow drain them without pulling them out and cleaning them out and put fresh fuel in them before trying to start the engine...Thanks Everyone for all the help and Happy New Year to All